96 blazer low gas mileage/ sluggish acceleration/ misfires

I have a 96 blazer, W-code engine SCPI (the one that looks like it has a huge throttle body on the center of the intake manifold, does not have the large Vortec pleneum on it). The truck gets about 10-12 mpg in the city and on a recent trip got about 15-16 mpg highway. After I did a tuneup, the check engine came on with the following codes po300, po174, po101, po171. Also showed missfires: cyl 1 1222, cyl 2 1053, cyl 3 1181, cyl 4 1736, cyl 5 2282, cyl 6 4276. The tech did a fuel pressure check and it held steady in the proper range when running and held for 15 minutes when shut off. I had done a complete tuneup (plugs,wires,cap,rotor,pvc,fuel filter,air filter). The engine still seriously hesitates from a dead stop on hard acceleration. The engine pops and sputters when you drop the throttle hard, until you let off the gas almost all the way, then it will slowly accelerate like it is running on only a couple of cylinders. After getting up to about 10mph it finally gets going. Does it both warm and cold. Feels like the engine is leaning out. Any ideas what may be causing this? I am at a loss. I can't afford to keep dumping gas money into this at this type of fuel economy. HELP!!!

Couple of things to check..(You have the Vortec engine btw, all engines are the same pretty much from 96 to current)..Check for arcing at the coil... Even without arcing you could have a bad coil...

Could also be a sticky injector. This won't necessarily mess up your fuel pressure...

But with all your codes, I'm thinking a bad or at the very least a dirty MAF sensor. When those things start acting up lots of stuff happenes including misfires. So I would suggest you pull the maf, clean it with Brake Clean and a soft toothbrush. Reinstall it, disconnect the battery for 20 mins, reconnect and see how it runs (let the computer relearn). If that doesn't do it it may be time for a new MAF.

Oh, and for giggles, you gapped your plugs to .060 right?

Yes the first thing I would check is a dirty Mass Air Flow Sensor, i just cleaned mine last week and It was like driving a brand new engine. I had hesitation, bad gas mileage, lost of power, bad acceleration, and cleaning the MAF cured all of that. If you clean it, be very careful of the thin, very thin wires, clean them very carefully, if one of those snap, you buying a new MAF, but give that a try and see how it works for you, thanks!

I have a 96 blazer, W-code engine SCPI (the one that looks like it has a huge throttle body on the center of the intake manifold, does not have the large Vortec pleneum on it). The truck gets about 10-12 mpg in the city and on a recent trip got about 15-16 mpg highway. After I did a tuneup, the check engine came on with the following codes po300, po174, po101, po171. Also showed missfires: cyl 1 1222, cyl 2 1053, cyl 3 1181, cyl 4 1736, cyl 5 2282, cyl 6 4276. The tech did a fuel pressure check and it held steady in the proper range when running and held for 15 minutes when shut off. I had done a complete tuneup (plugs,wires,cap,rotor,pvc,fuel filter,air filter). The engine still seriously hesitates from a dead stop on hard acceleration. The engine pops and sputters when you drop the throttle hard, until you let off the gas almost all the way, then it will slowly accelerate like it is running on only a couple of cylinders. After getting up to about 10mph it finally gets going. Does it both warm and cold. Feels like the engine is leaning out. Any ideas what may be causing this? I am at a loss. I can't afford to keep dumping gas money into this at this type of fuel economy. HELP!!!

I too have a 96 and I too had same problems. And it was all due to MAF THe O2 sensors and MAP sensor and plugs twice oil and filter. basically a total tune up. I also took her in to make sure i wasn't missing anything. prefer not go into details on that.(I was ripped-off). But, now she runs strong. gets excellent gas millage, and I am happy.

I have a 96 blazer, W-code engine SCPI (the one that looks like it has a huge throttle body on the center of the intake manifold, does not have the large Vortec pleneum on it). The truck gets about 10-12 mpg in the city and on a recent trip got about 15-16 mpg highway. After I did a tuneup, the check engine came on with the following codes po300, po174, po101, po171. Also showed missfires: cyl 1 1222, cyl 2 1053, cyl 3 1181, cyl 4 1736, cyl 5 2282, cyl 6 4276. The tech did a fuel pressure check and it held steady in the proper range when running and held for 15 minutes when shut off. I had done a complete tuneup (plugs,wires,cap,rotor,pvc,fuel filter,air filter). The engine still seriously hesitates from a dead stop on hard acceleration. The engine pops and sputters when you drop the throttle hard, until you let off the gas almost all the way, then it will slowly accelerate like it is running on only a couple of cylinders. After getting up to about 10mph it finally gets going. Does it both warm and cold. Feels like the engine is leaning out. Any ideas what may be causing this? I am at a loss. I can't afford to keep dumping gas money into this at this type of fuel economy. HELP!!!

Sounds like a MAF or a coil overheating.